It is a typical practice of state and local water departments to flush water mains and hydrants periodically. The flushing may take place as part of an ordinary maintenance program. Alternatively, a hydrant may be flushed as part of new construction, for instance in a new subdivision, as water pressure and pipes are being prepared for use. Hydrant valves are open to a "full open" position so that maximum fluid flow will be allowed in order to achieve maximum efficiency of the maintenance or installation process.
Fire main hydrants can be mounted in various locations, but, typically, they are positioned along street curbs in areas where access to the hydrant could become necessary. In many instances, these locations are in residential neighborhoods.
Because of the construction of fire main hydrants, when they are flushed they typically produce a water discharge having high energy and exerting significant force upon any object which might come into its path. Typically, the water flow generated during hydrant flushing is in a fixed direction, the direction of discharge not being able to be varied. As can be seen, therefore, hydrant flushing can pose a substantial safety problem. This is especially true in view of the frequent presence of such hydrants in residential neighborhoods where children can be found. It is not unrealistic to expect that injuries could readily occur as a result of the flushing of a hydrant. As a result, hydrant flushing typically requires the blocking of traffic and the presence of monitors to protect vehicles and pedestrians.
In addition to this potential personal injury, the high pressure, high flow of water from a hydrant can cause substantial environmental damage to landscaping around a hydrant. Consequently, washout erosion damage can result. Further, water line sediment built up in the water system may cause further pollution or unsightliness.